1. Field of the Invention
The present invention relates to an image capture apparatus that uses a solid-state image sensor, and a method for processing a defective pixel in an image capture apparatus.
2. Description of the Related Art
In recent image capture apparatuses, the number of pixels in a solid-state image sensor, as represented by a charge-coupled device (CCD) sensor and a complementary metal oxide semiconductor (CMOS) sensor, for example, has been increasing. With this increase, the occurrence of defective pixels (flaws) on the image sensor has also been increasing. Examples of defective pixels include production flaws that are produced during the production process of the image sensor, and growth flaws that occur after being mounted in the image capture apparatus. Among growth flaws, some flaws can be further categorized as temperature-characteristic-dependent flaws that increase and decrease during usage dependent on the temperature of the image capture apparatus. Among such defective pixels, for the production flaws, the flaws are corrected in advance by capturing a black image when shipped from the factory, and detecting the position of the defective pixels. Further, for the growth flaws, the defective pixels can be detected and corrected by capturing a black image by forcibly blocking light from the image sensor when turning the power on. However, in the above methods, the temperature-characteristic-dependent flaws that occur during usage of the image capture apparatus dependent on temperature changes cannot be detected.
Japanese Patent Application Laid-Open No. 2004-015191 discusses a method for detecting and correcting defective pixels from a captured image. In the method discussed in Japanese Patent Application Laid-Open No. 2004-015191, the luminance of each pixel is compared with the luminance of surrounding pixels, and pixels that have a luminance different by a predetermined level or more are determined as being white flaws.
However, in the method discussed in Japanese Patent Application Laid-Open No. 2004-015191, in the output of an image sensor that includes focusing pixels, since the difference between the output value of the focusing pixels and the output value of the imaging pixels is large, there is the problem that the output value of the focusing pixels is recognized as a pixel defect.